The Gnostics and Their Remains, by Charles William King, , at sacred-texts.com
Macrobius seems to afford us some clue for solving this enigma by his remarks upon the true universality of the sun-worship under different names (Sat. i. 19). "That under the form of Mercury the Sun is really worshipped is evident also from the Caduceus which the Egyptians have fashioned in the shape of two dragons (asps), male and female joined together, and consecrated to Mercury. These serpents in the middle parts of their volume are tied together in the knot called the 'Knot of Hercules;' whilst their upper parts bending backwards in a circle, by pressing their mouths together as if kissing complete the circumference of the circle; and their tails are carried back to touch the staff of the Caduceus; and adorn the latter with wings springing out of the same part of the staff. The meaning of the Caduceus with reference to the nativity of man, technically termed his genesis (or horoscope), is thus explained by the Egyptians: they teach that four deities preside and attend at man's birth--the Daimon (his genius), Fortune, Love, and Necessity. By the two first of these they hold that the Sun and the Moon are meant; because the Sun, as the author of spirit, heat, and light, is the producer and guardian of human life, and therefore is esteemed the Daimon that is the god of the person born. The Moon is the Fortune, because she is the president over our bodies which are the sport of a variety of accidents. Love is signified by the kissing of the serpents; Necessity, by the knot in which they are tied. The reason for adding the wings has been fully discussed above. For a symbol of this nature the convolution of the serpents has been selected in preference to anything else, because of the flexuosity of the course of both these luminaries. From this cause it comes, that the serpent is attached to the figures both of Aesculapius and of Hygiea, because these deities are explained as expressing the nature of the Sun and the Moon. For Aesculapius is the health-giving influence proceeding out of the substance of the
[paragraph continues] Sun, that benefits the souls and bodies of mortals. * Hygieia again is the influence of the nature of the Moon, by which the bodies of things animated are holpen, being strengthened by her health-giving sway. For this reason, therefore, the figure of the serpent is attached to the statues of both deities, because they bring it about that our bodies strip off, as it were, the slough of their maladies, and are restored to their pristine vigour, just as serpents renew their youth every year, by casting off the slough of old age. And the figure of the serpent is explained as an emblem of the Sun himself for the reason that the Sun is perpetually returning out of, as it were, the old age of his lowest setting, up to his full meridian height as if to the vigour of youth. Moreover, that the dragon is one of the chiefest emblems of the Sun, is manifest from the derivation of the name, it being so called from δέρκειν, 'to see.' For they teach that this serpent, by his extremely acute and never-sleeping sight, typifies the nature of the luminary; and on this account the guardianship of temples, shrines, oracles, and treasures is assigned to dragons. That Aesculapius is the same with Apollo is further proved by this fact, not merely that he is reputed the son of the latter, but because he also is invested with the privilege of divination. For Apollodorus, in his Treatise on Theology, lays down that Aesculapius presides over augury and oracles. And no wonder; seeing that the sciences of medicine and of divination are cognate sciences: for medicine predicts the changes for good or ill about to succeed in the human body. As Hippocrates hath it, the physician should be competent to predicate of his patient 'both his present, his past and future condition,' which is the same thing as divination which foreknows, as Homer says,
It has been already stated how, in the Mithraic worship, the image, surrounded from foot to head by the spiral convolutions of the serpent, had become the established emblem of the deity himself. The incidental remark in the above citation, that the
flexuous motion of the reptile represented to the Egyptians, the annual course of the sun, affords the sufficient reason why his image should be thus encircled by so significant an attribute. Taking therefore into account the fact that the disputed symbol we are considering was by its nature primarily confined to talismans designed for medical agents, there is at once sufficient reason to suppose it connected with the worship of Aesculapius; and secondly, as it always appears in such cases in company with the Agathodæmon, the undoubted emblem of the Solar god, it may be inferred to be either a symbol or a hieroglyphical representation in little of the same type. In other words, the figure signifies nothing more than a serpent-entwined wand, and its sense only contains an allusion to the principal visible manifestation of the nature of the Sun. But this point must he left for fuller examination in its connexion with the hitherto unexplained Sigil which invariably makes its appearance on the reverse of the Chnuphis talismans, and which therefore must have been regarded as an essential element in their potency.
177:* Or in modern scientific phrase, Aesculapius is but another name for electricity.